Centrifugal slurry pumps generally include a pump casing comprising a main casing part and one or more side parts. The pump may also comprise an outer housing which encases the pump casing. In this latter arrangement, the pump casing is configured as a pump liner which is typically formed from hard metals or elastomers. An impeller is mounted for rotation within the casing about a rotation axis. The main casing part has an outer peripheral wall section with an internal surface which may be of volute form, a discharge outlet and an inlet which is at one side of the casing and coaxial with the impeller rotation axis. The impeller typically includes a hub to which a drive shaft is operatively connected and at least one shroud. Pumping vanes are provided on one side of the shroud with discharge passageways between adjacent pumping vanes. In one form of impeller, two shrouds are provided with pumping vanes being disposed therebetween. The pumping vanes include opposed main side faces one of which is a pumping or pressure side face. The pumping vanes further include a leading edge portion in the region of the inlet and a trailing edge portion in the region of the outer peripheral edge of the or each shroud. The leading edge portion is inclined with respect to the inlet at a vane inlet angle.
One of the side parts can define a pump intake. In many applications the pump intake includes a protruding section of entry pipe which is generally arranged so as to be horizontally disposed, also having a lateral plate extending from the periphery of the said entry pipe. The entry pipe and lateral plate piece portion is often referred to as a front liner suction plate or a throatbush.
For slurry pumps handling heterogeneous slurries (with settling particles of typical size 0.5 mm) it is common for there to be a solids concentration gradient weighted towards the bottom of the horizontally-disposed inlet pipe. Because the concentration of solids is greater at the bottom of the pipe due to settling, the velocity of the particles at the bottom of the pipe is reduced relative to that at the top of the pipe. The implications of this skewed velocity and concentration gradient on the optimum design of the impeller are significant. Impeller pumping vanes are usually designed for “shockless” entry of the fluid onto the impeller pumping vanes.